The closest prior art known to applicant is U.S. Pat. No. 3,644,861 to Aloysius Fister, 02/22/72 for PROTECTOR FOR ELECTRIC CIRCUITS. According to that patent the casing of a fuse is provided with annular grooves adjacent opposite ends of the outer surface thereof and has yieldable annuli disposed within those grooves. The axially inner edges of the ferrules are cold formed into said annuli and thus firmly positioned relative to the casing of the fuse. The deformation of the annuli sets up a force of reaction opposite to that exerted upon the annuli by deformation of the ferrules. This force of reaction can be sub-divided into two components of which one is in a direction longitudinally of the fuse tube and the second is at right angles to the former. The component in a direction longitudinally of the fuse tube is useful since it tends to maintain the ferrules in position. The component at right angles to the longitudinal component is useless, or even undesirable, since it tends to expand the ferrules in radial direction. To obtain a given component in axial direction requires relatively large annuli, and relatively large grooves in the casing of the fuse which tend to weaken the latter.
It is the prime object of this invention to provide a means for affixing ferrules to a fuse casing, particularly a casing which is made of a material that has little resiliency, which is free from the above limitations.